Introducing GIF in Photoshop

The GIF format was one of the earliest image file formats developed for online display. It was created back in the 1980s, even before the government-supported predecessor of the Internet (called ARPANet) was transformed into the public information highway we have today. The GIF format’s earliest use was at CompuServe, back in the days when dial-up modems moved information at a sluggish 300 baud (roughly 100 times slower than the average dial-up connection today). As you might guess, the impetus to speed up image downloads was intense.

GIFs produce smaller files by discarding some colors, if necessary, to produce a file that has a maximum of 256 different colors. Similar colors are combined into fewer hues, or represented by a pattern of similar colors (called dithering) that the eye merges into an approximation of the original range of colors. If an image already has 256 or fewer colors, you may not have to discard any colors. Or you can choose to reduce the number of colors anyway to produce an even smaller file size. Although reducing the number of colors in a full-color image can produce an artistic effect in most cases you must reduce colors with care. The GIF format’s 256-color palette is called indexed color.

The kind of compression used for GIF files is called lossless compression because the image can be uncompressed and reconstructed exactly as it was before compression. Of course, information is lost when colors are discarded prior to compression (when you optimize the number of colors); indeed, Adobe includes a GIF option called lossy, but that’s another story.

GIF advantages
These are the advantages to using GIF files:
- GIF files can be very small in size. If you start with an image that has few colors in it, GIFs can be positively tiny. I’ve converted some logos with three or four colors into files that are smaller than 1K. You can use a full 256 colors, slim down to a trim 128 colors, or try to get away with 64 or 32 hues if your subject matter lends itself to serious reduction.
Bottom line: GIFs are great for images with 256 or fewer colors and can be useful with many images with more colors, too.
- GIFs preserve the sharpness in your original image. Because no pixels are discarded (only colors), sharp images remain sharp.
Bottom line: GIFs are excellent for line art, charts, graphs, cartoons, logos, and most other images that emphasize solid areas instead of continuous tones.
- GIFs can be interlaced. In this process, every eighth line is displayed as the file begins to be downloaded, providing a rough image that can be viewed immediately. The other lines are filled in until the full image is available.
Bottom line: Interlacing is mostly useful to visitors who have slow connections. Virtually all graphics-capable browsers can display interlaced GIFs, but not all can display interlaced PNG or Progressive (JPEG’s flavor of interlacing) JPEG images.
- GIFS can be made transparent. You can make a single color transparent to the browser so that the underlying background shows through.
Bottom line: This is a great feature for creating “floating” images.
- GIFs can be animated. Browsers display multiple GIF images consecutively as animations.
Bottom line: This is a great feature if you don’t overdo it by creating animations that are huge and take a long time to download or that are annoying to visitors.

GIF disadvantages
Here are a few disadvantages to using GIF files:
- Other file formats may produce smaller file sizes. Depending on the content of the image, a well-optimized JPEG or PNG file can be smaller. Whether a GIF file is smaller than a JPEG or PNG file depends on the number of colors in the original and how well those colors can be combined in a JPEG or PNG file without losing too much information. Of course, when you compare the file size, you should also compare the image quality. After all, the proof is in the pudding.
Bottom line: Always compare the file size of GIF and JPEG images by using the Save for Web feature to see which format provides the smallest file.
- GIFs don’t preserve the colors in your images. Continuous-tone images, particularly those with fine gradations of color (even something as simple as a drop shadow), may display with objectionable bands of color in GIF format.
Bottom line: Use GIFs for graphics, especially those with broad areas of color, and use other formats for photographs, in which a wide range of colors is important.